OBJECTIVE: To determine the loss in brain substance and the alteration in brain function, 8-10 years after brain damage incurred during the Vietnam war. The resource for this is a Registry of 1500 Head Injuries compiled in the field by Military Surgeons from 1967 to 1970. The characteristics of the injury and the initial disability is recorded in detail, according to a prospective plan. To achieve this objective, a plan has been developed, titled Phase I, and a team assembled to a) collect, review and analyze the intervening medical records and b) plan Phase II. The latter will utilize an unique approach to the loss or alteration in structure, i.e., computerized axial tomography, and other techniques, not available in previous studies of sequelae. A Feasibility Study for Phase I was initiated in the Autumn of 1976.